Scene View Extension

Adds an MSAA toggle to the Scene view toolbar, letting you control rendering anti-aliasing and the selection outline together.

Detailed settings are in the SceneView tab of the window opened via さたにあしょっぴんぐ/エディタカスタマイザー/Editor Setting (Satania Shopping / Editor Customizer / Editor Setting) in the main menu. The button can be shown or hidden from the Overlays menu at the top right of the Scene view.

MSAA

When turned on, the Scene view is rendered with anti-aliasing, so you can tweak materials and the like in a less jagged view that is closer to the final appearance.

• The MSAA level can be switched from the ▼ menu to the right of the button (QualitySettings に追従 (Follow QualitySettings; the default) / 2x / 4x / 8x). The level can also be changed from the SceneView tab of Editor Setting
• Built-in RP only (the button is disabled on URP / HDRP)

Credits

The MSAA technique is based on lilEditorToolbox by lilxyzw (MIT License).

Selection Outline

The ▼ menu lets you switch the selection outline between three options: OFF / Unity 標準 (Unity Default; the default) / Custom (Unity 標準 is the same setting as in the Gizmos menu).

• Custom — draws an outline in custom colors instead of Unity's default one. The line colors (selected object / child objects; alpha = intensity) and the fill opacity are set in the SceneView tab of Editor Setting. The mode (OFF / Unity 標準 / Custom) can also be switched from the popup in the same tab

The selection outline may look thicker

The highlight line around selected objects (Selection Outline) is a post-process that assumes no MSAA, so while MSAA is on, the line may become thicker or appear inside fine meshes such as hair. If this bothers you, turn Selection Outline OFF from the ▼ menu.